1. Field of the Invention
The present invention relates to a method for treating an chlorinated organic compound present in a polluted environment, particularly a soil or a ground water by dechlorination.
2. Description of the Related Art
Heretofore, as treatment methods of chlorinated organic compounds, various physical/chemical and biological methods have been used. In the case that a ground water is polluted with the chlorinated organic compound, a method is usually utilized in which the polluted water is pumped and then aerated to remove the chlorinated organic compound from the ground water. Furthermore, as another treatment technique of the water containing the chlorinated organic compound, there is a method in which the chlorinated organic compound is decomposed by the irradiation of ultraviolet light. In the case of the pollution at an extremely low concentration, a method can be utilized which comprises dissolving hydrogen in the polluted water, and then bringing it into contact with the surface of a metal to carry out dechlorination (Japanese Patent Publication No. 2412/1980). On the other hand, for the treatment of the chlorinated organic compound present in water in a soil or among soil masses, there can be used a vacuum extraction method which comprises a suction step by the utilization of reduced pressure, an on-site or an off-site burning method which comprises digging out a polluted soil, and then subjecting it to a burning treatment, a heat desorption method which comprises releasing the chlorinated organic compound from the soil by heating, and a soil cleaning method which comprises oozing out the chlorinated organic compound by the use of water or another solvent. In addition, as a purification method for a low-concentration pollution in a wide range, a bioremediation method utilizing microorganisms has also been investigated.
However, the above treatment methods all have the following problems regarding treatment efficiency, cost, easiness and the like.
Firstly, of the above treatment methods, the physical/chemical treatment method requires facilities and apparatus for separating the chlorinated organic compound from the environment and then treating it, and for the installation of the facilities, their operation and maintenance, a great deal of cost is required. On the other hand, in the bioremediation method in which a biological treatment is done, it is necessary to properly control a temperature, a pH, the concentrations of nutrient salts and dissolved oxygen, and the like for the purpose of keeping up the activity of micro-organisms for the treatment, and hence an apparatus for continuously adding oxygen and the nutrient salts to the environment is required.